Boston Marathon bomber Dzhokhar Tsarnaev is a terrorist who wanted to punish America with a deadly 2013 attack, a federal prosecutor said on Wednesday as the government urged a jury to sentence the 21-year-old to death.

Citing a note that Tsarnaev wrote while hiding in a boat, bleeding, after a gunfight with police four days after the April 15, 2013, attack, Assistant U.S. Attorney Steven Mellin said the ethnic Chechen had turned against his adopted country.

“He wrote, ‘Now I don’t like killing innocent people, but in this case it is allowed because America needs to be punished.’ … These are the words of a terrorist who is convinced he did the right thing,” Mellin said.

“He killed indiscriminately to make a political statement. … His actions have earned him a sentence of death.”

Following closing statements, the same jury that last month convicted Tsarnaev of killing three people and wounding 264 others in one of the highest-profile attacks on U.S. soil since Sept. 11, 2001 will begin deliberations on whether to sentence him to death by lethal injection or life in prison without possibility of release.

Mellin showed the jury photos of the bombing’s immediate aftermath, with victims whose legs were blown off sitting in pools of blood, and another image of a 29-year-old restaurant manager screaming in pain before she died of her injuries.

The defense, meanwhile, described Tsarnaev as an adrift teenager under the spell of his 26-year-old brother, Tamerlan, who they contend was the architect and driving force behind the bombing and the murder three days later of a police officer.

TAMERLAN’S INFLUENCE

Defense attorneys noted that when Dzhokhar’s parents returned to their native Russia in 2012, he was left under the influence of Tamerlan, who had become obsessed with becoming a jihadist. Tamerlan also briefly returned to Russia.

“The horrific events of the Boston Marathon bombing cannot be told or understood with any degree of reality without talking about Tamerlan,” defense attorney Judith Clarke told jurors. “Tamerlan left the United States wanting to wage war. He was rejected as a warrior. … He came back to the United States as a jihadi wannabe. He couldn’t fit into any movement, so he would create his own.”

Clarke showed a photo of Tamerlan wearing an Arab headdress and holding a handgun in front of a white flag with Arabic writing. She noted that Tamerlan and the Tsarnaev’s mother, Zubeidat, both stunned their family back in Russia when they turned to militant Islam.

Tamerlan died in the chaotic hours that followed that slaying, after the gunfight with police that ended when a fleeing Dzhokhar inadvertently ran his brother over with a car.

Defense witnesses included some of his Russian family members, who remembered him as a beloved child, and a Roman Catholic nun and prominent death penalty opponent who said she believed Tsarnaev was “genuinely sorry” for the pain the attack caused.

The jury must determine whether Tsarnaev deserves to be sentenced to death or to life in prison for each of the 17 capital counts of which he was convicted. The jury need only to sentence him to death for one of those counts for him to face the possibility of execution.

Defense lawyers would likely immediately appeal a death sentence.

The jury heard from about 150 witnesses through the trials’ two phases but never from Tsarnaev himself. The defendant sat quietly and showed no emotion, other than a brief moment last week when he dabbed at his eyes when his 64-year-old aunt broke down in tears on the witness stand and was unable to testify.

The death penalty remains unpopular in Massachusetts, where it is not allowed under state law, and opinion polls have showed more residents opposed the idea of putting Tsarnaev to death than support it.

Their ranks include the family of 8-year-old Martin Richard, the youngest person to die in the blasts, and the sister of Massachusetts Institute of Technology policeman Sean Collier, who was shot dead by the Tsarnaevs.

The other two people killed in the bombing were 23-year-old Chinese graduate student Lingzi Lu and 29-year-old Krystle Campbell.

While admitting, as she had in the trial’s first day, that Dzhokhar committed all the crimes with which he was charged and then convicted, she said the bombing would not have occurred if Tamerlan didn’t push it forward.

“Dzhokhar Tsarnaev is not the worst of the worst. And that’s what the death penalty is reserved for, the worst of the worst,” Clarke said. “A sentence of life in prison without possibility of release reflects justice and mercy. Mercy is never earned, it is bestowed. And the law allows you to choose justice and mercy.”